Method and means for recovering certain constituents from gaseous bodies.



METHOD AND MEANSVFOR RECOVERING CERTAIN. CONSTITUENTS FROM GASEOUS BODIES.

APPLICATION FILED IULY 23. 19H.

1,204,906.Y Patented Nov, 14, 1916.

.STATES PATENT OFFICE.

-WALTERIAUGUST SCHMIDT, OEIOS ANGELES, CALIFORNIA, AND'LINN BRADLEY, OF

EAST ORANGE, NEW JERSEY, AssIGNORs To RESEARCH CORPORATION, OE NEW E oRK, N. Y., A CORPORATION OE NEW lYORK.

METHOD ANE'MEANS EOR RECOVERING CERTAIN CoNsTITUENTS ERoM GASEOUs 'v To all whom it may 'concern E@ a known that We, wALTERAaUST SCHMIDTand LINN BRADLEY, citizens of the United States, residing, respectively, at

LosAngel'es, in thecou'nty of Los Angeles and State of California, and at'East Orange,

. in the county OfEssex and State of New Jersey, have invented new and useful Methconsisting of a number of constituents Which'4 pleX gaseous V ods. and Means for Recovering Certain Constituentsfrom Gaseous Bodies, of which the following is 'a specification,

Our inventlon relates in general'to the 'separation of'various constituents of c omf bodies, and also to the separa` fit would be of advantage to separate, so as to recover valuable constituents from .the gases, but such vseparation and recovery` has not `been practicable with l.the methods heretofore proposed. 4There are also many,Y instances in which such gases carry fromthe furnace or generator,certain;quantitiesv of. solid material, such'v as dust, Vwhich .it is desirable to separate `from the recovered products, sov ,thatv thelatterfwill be free from such dust'or'otherimpurities The main object of Iour Inventionfis to provide for'rapid, economical and substan-v der'rsabilityV will'. be'* successlvelyi'."brought.'

est importance that this precipitation of the` cloud should be effected: quickly and thor precipitation .entcondensabilityfin tially complete, s ep'arationjofthe different substances contained this 'character.

. controlling lthe temperature thereof ,vi such manner that the substances ofdifigerent confroml a. gaseousv vform [to z'ondition` of suspended particles forming a'.`cloud and by, substance, as

before thecondensation ofthe ding product. It is ofthe great- Specification Of Letters Patent.

.ouglily, sonthnat each vsubstmcebei-ng separated 'may be fully or adequately precipigta'ted. before the temperature changes sufficiently to produce a .cloud of a substance requirlng a lower temperature for its condensation. The usual methods of removal of the suspended .particles from the gases,

settling or by washing orscrubbing with hquid are not practicable in such a process of multi-stage separation;- Precipitationin.

Patented Nov. 14,' 1916. Appuoagion mea`1u1y2a, 191 4. seriaiNo. $52,584.

settling chambers is SO slow and requiresv suchlarge chambers that it is difiicult,` if l c5 v of `temperature uniform throughout any one notlimpossible, Vto maintain the conditions precipitating-stage, with'nthe result that the product-corresponding to'that stageis coni" tan'ilnated with those'of preceding and suc-' ceedingy stages, and the separation vof the constituentsof the gaseous body is therefore. not sharp and .co'mpletej Moreover a succession of such settling operations, in large chambers requires such-alarge plant as to make the process :unduly expensive 'Separation by .spraying with liquid is, of

course, out ofthe question, sincethel Vrel sultant cooling ofthe gaseous body would i-nterfere with the proper control of the tem- `peratures, as requiredgby `the process.

- Ve have foundthat bysubjecting the gas Y :tothe action of an electric discharge in an g electrostatic field', the; suspended particles or cloud" can be removed or precipitated so quickly and eectively that substantially .complete precipitation of any *one of the different constituents or substances in the v'1 'gaseous body [may bev Veected almost in# stantaneously, and before 'thereisany opport-unity for change fof the temperature or other conditions, so that ajsharp separation {wof the different constituents o'rsubstances maybe thereby obtained.: 4'Moreover the pre cipitating operation as so carried out, 1s so rapid .thatfa number of Successive separa'- tions j pense, 'f'iwithin 'the may be' effected without undue exan'd the process is thereby brought limits L of commercialv practica' bility. Ournve jectirig the 'gaseous' tion" consists essentially in sub-- ody to a successlon ofelectrical precipitating actions with control` I' of temperature, 'so as to produce, between Successive precipitationmeduction of telnlparatus capable site conditions of temperature control and pcrature sufcient to condense, in the form of a cloud mist or fume, one of the constituents of the gaseous body, which is then removed in the next succeeding precipitation.-

Our method may be carried out in any apofmaintaining the requiof providingfor the multi-stage precipitation by electrical action. Suitable forms of apparatus for carrying out the process are illustrated in the accompanying drawings, wherein:

`igure 1 is a vertical section of an apparatus suitable for application of our invention in connection with the recovery of arsenic or other condensable constituent from the Hue-gases apparatus being adapted to` perform two successive precipitations, for removal, successively, of the solid suspended dust and of the condensable constituent. Fig. 2 is a vertical section of a precipitating apparatus adapted for carrying out our method where a plurality of condensable constituents are to be recovered separately. Referring to Fig. l, the apparatus thereln shown comprises a roaster or furnace 1, for roasting or heating the flue dust, ore or other material, means for conducting away the gases from such roaster or furnace, and

a plurality of precipitating devices 2 and I nace or roaster 1 and th 2 connected to receive such gases and adapted to perform successive precipitating actions thereon. The furnace or roaster may be of any usual or suitable construction, comprising, for example, a combustion chamber 3 and a mechanical roaster-chamber 4:, to which the ore, lue dust or other material in a divided condition, per or feed'means 6.

Suitable pipe connections l0, 11 and 12 are providedfor leading the gases from the outlet 8 of the furnace or roaster successively throughthe precipitators 2 and 2', andfrom the last precipitator to any suitable ue or stack, a blower 13 being provided at any desired point in such connections for drawing or forcing the gases through the precipitators. 'A damper 9 1s provided i'n pipe 11 for regulating the 1ntensity of draft, and valved air-inlet means 14 .is provided for admlttlng cool air from the outside to this pipe, so as to properly control the temperature.

Each precipitator comprises a suitable casing orl chamber, formed for example, asI a series of ipes 15, connected to top and.' bottom hea ers 16 and- 17, and collecting' and discharge electrodes 'areprovided in each precipitator, the pipes 15, for example constituting the collecting electrodes, an

the discharge electrodes consisting of fine wires 18 suspended from insulated supports 19. Connections are made to said electrodes of an ore roaster, thisl is supplied by a l1op-A gases below the tion point of the arsenic, which, thencon-- from a source of high tension unidirectional current, for example, a step-up transformer 20 and a rectifier 21 connected therewith, said rectifier and the collecting electrodes having ground connections and the high tension side of the rectifier being connected by a wire 24e to the supports 19 for the discharge electrodes 18. Suitable means 25 .are provided at the bottom of each precipitator, for recovering and discharging the precipitated substance.

The following example will serve to illustrate our method, as applied to metallurgical work. In roasting certain ores, having a high arsenic content, gases are given off which contain, among other constituents, the products of combustion, which in most cases will be high in sulfur dioxid, nitrogen, etc., and large quantities of arsenic in the form of volatilized arsenious oxid, which in many cases will b e valuable for recovery, if it can be recovered comparatively pure. The gases passing from the roaster also carry large quantities of dust suspended therein and the presence of this dust interferes with recovery of the arsenic in pure condition from the' gases, vas it tends to contaminate the arsenic product.

ur inventin provides for recovery ofthe arsenic, substantially free from contamination by flue-dust, in the following manner: The ore is heated or roasted in the fure arsenic content of the ore is thereby carried off, in the form of arsenious oxid, in the gases which pass from the roaster to the first precipitator 2, together with the other products of combustion and with the dust carried over mechanically by the gases. he gases are delivered to t e first precipitator at a temperature suiiicientlyv high to maintain the arsenic in a volatilized condition, and such temperature is maintained whilethevgases are passing through the iirst precipitator.

suiiicient potential difference is maintained between the electrodes of this precipitator, to produce ionization 'and discharge at the discharge electrodes 18, with the res ult that the dust particles suspended in the gases are charged and are forced by the action of the electric field between the electrodes to travel toward the collecting electrodes', on which they `are precipitated, the dust so precipitated being removed from the electrodes from time to time in any suitable manner. This operation leaves the ases in clean condition, as far as any solid or liquid particles are concerned, and the clean gases then pass through the pipe 11, wherein they are cooled by any suitable means, for example by admitting cool air from the outside, through the ports or valved inlets 14, so as to reduce the temperature of the condensation or sublimadenses to-a mist or cloud of suspended par-4 ticles. The gases, with the mist of arsenic suspended therein, are then forced by the blower 13 to the second precipitator 2 wherein the arsenic dust or mist is precipil tated by electrical action and is recovereda substantially free from dust, this precipif tated arsenic being removed from the collecting electrodes and from the casing of the precipitator either continuously or from time to time, by any suitable means.

In case Athe gases being treated contain more than onecondensable constituent, our process may provide for successive separation of several different constituents of diffe'rent condensability. Thus, in the example above given the gases bearing the arsenic in the form of vapor of arsenious oxid, may

also contain other substances, for example sulfuric acid, and such other substance or substances may then be separated from the gases by passing the latter through a second cooling means to further reducethe temperature, so as to condense the sulfuric acid or other substance, the gases with the condensed sulfuric acid in the form of mist being then led or drawn through a third precipitator, wherein the sulfuric acid is precipitated. In carrying out this three stage method, the apparatus shown in Fig. 2 may be yused, the pipe l0 in this'ease leading from the roaster or furnace flue to the first precipitator, and.

the several prcipitators 2, 2 and 27 being connected in series by suitable piping, a blower 13 being yprovided yfor forcing or drawing the gases through the apparatus. In some cases, for example in the caseof sulfuric acid precipitation, it niay be desirable to humidify the gases to facilitate the condensation, and for this purpose the pipe 1l between the secondi and third precipitating devices may be provided with water supply means 29 for spraying water into the y gas, as well as with'the air-admission means 14. In some cases the cooling may be effected by liquid spray alone without air admission, or it may be effected by other means. In carrying ut our method in this. separation, the dust or solid or liquid sus- .pended matter.. :passing into the apparatus from the roasterA or furnace is first precipitated by the action of the first precipitator 2,' the gases are then cooled by admission of air in the piping 11, the first condensation product, for example, arsenic, being thereby condensed .and immediately thereafter cprecipitated in the second precipitator 2 yand the gas being then further cooled by admission of water or water and air in the piping 11 so as to condense the second condensate, for example, sulfuric a'cid, which isD then precipitated by electrical action in the third precipitator 2". .The sulfuric acid may be drawn of from this precipitator for use, but

in some cases the object of the removal of the sulfuric acid from the gases may be only to avoid its presence in the effluent to theatmosphere. n

Any other means of cooling the gases to condense a constituent,l thereof 4to a cloud or mist, may be used in additioii'-ff to` or instead of the means above describedf` For example, l

having a lower vapor tension may be condensed; this way we may gprovide'for separation of constituents which have approximately the same lboiling points,pro

ferent.' In such cases the procedure will be to firstcool by admissionof air, to a tem- `perature somewhat below the boiling point,

thereby condensing the constituent of'l lower vapor tension, but retaining the other constituent in the gas; then precipitating such vided their vapor tensions slightly below thel boiling temperature are'markedlv diff condensed constituent, and then'cooling furi ther by radiation, so as to condense said other constituent and precipitatingthe latter. This method may also be used for separating gaseous constituents whichsublime directly as solids provided their vapor pressurecurves have markedly different charac-y teristics.

It will be understoodthat in carrying out.l

our invention the temperature stages may be so controlled vasv to separate the several v constituents with any desired degree of sharpness, and incase only partial separation is desired, the temperature control will be such as to give the required percentages of the several constituents in each product.

Inasmuch vas the condensation point for any particular constituent of the gasl depends on the pressure, aswell as on thetemperature, we lmay provide'for controlofthe successive'condensation by vvarying or controlling the pressure. This may be effected with the apparatus shown, by properly con' trolling the dampers and inlets, and by controlling the speed of the fan, or it. may be effected` in other ways.

condensation thereof, either tol solid or to liquid form, will take place.

What we claim is:`

ldifferent' condens'ability from gases contain! ing the same, and from lone another, which By condensationv point or temperature -of the gaseous constituent, we mean a temperature at which some 1. The method of separating substances of rality of electrical precipitating actions, and

' controlling the temperature so as to reduce the temperature between the precipitating actions sufficiently to condense into the form of-cloud, one of the constituents of the gas, for precipitation in the next succeeding precipitating action.

2. The method of recovering a condensable constituent from a gas containing the same and also containing suspended particles, which consists in subjecting the gas to the action of an electric discharge in an electric field, to cause precipitation of the suspended particles, then cooling the gas to condense said condensable constituent, in the form of cloud, and then again subjecting the gas to the action of an electric discharge in an electric iield, to precipitate the said cloud.

3. The method of recovering certain constituents of gaseous bodies, which consists in the formation of clouds, of the individual materials to be recovered, by cooling the gases below the condensation point of the most condensable constituent but maintaining the temperature above the condensing point of the next most condensable constituent, so as to condense only the most condensable constituent, in the form of cloud,

subjecting the gases while maintained at the stated range of temperature, to precipitating actionto separate the said cloud therefrom, then reducing the temperature sufficiently to condense only the next most condensable constituent, and precipitating the same while the gas is maintained at such temperature, the operation of cooling, condensation and precipitation being repeated until the required material of lowest condensability has been separated from the gases.

et. The method for separation of dust and fume from certain condensable constituents in gases, which consists in first subjecting the gases to electrical discharge in an electric: field to precipitate the dust andfume therefrom, then cooling the gases to such a temperature as to cause condensation only of the 'most condensable constituent, then subjecting the gas to the action of an electric discharge in an electric field, to precipitate the cloud formed by condensation of such constituent; and repeating the operations of cooling to definite tempera-tures to form clouds of definite constitution `and of precipitation of such clouds, until all the required constituents have been removed from the gases.

5. The. method of separating a condensable constituent from a gas, which consists in mixing a cooler gas with the gas to be treated. so as to reduce the temperature of the mixture below the temperature of con- `densation of such constituent, 'and thereby cause` condensation of such constituent in the form of a cloud, and then passing the gas containing the cloud through an electric field, in which an electric discharge is maintained, to precipitate the cloud from the gas.

6. The method of separating a condensable constituent from a gas, which consists in cooling the gas below the temperature of condensation of such constituent, and simultaneously adding moisture thereto, to humidify the gas and thereby facilitate condensation of said constituent therefrom in the form of a cloud, and then subjecting the gas to electrical precipitating action to precipitate such cloud.

7. An apparatus for recovering certain constituents from gaseous bodies, comprising a plurality of electrical devices for producing electric discharge in an electric field, means for conducting the gas to be treated successively through said electrical devices, and means for reducing-the temperature of the gas as it passes from each of said electrical devices to the next electrical device, so as to cool the gas by a pluraity of successive steps, the cooling at each s ep being sufficient to cause some constituent of the gas to be condensed in the form of a cloud, and the cloud so formed being precipitated in the next succeeding electrical device.

S. An apparatus for recovering certain constituents, of different condensability, from a gas, comprising means for successivelv cooling the gas to temperature at which the respective condensable constituents will condense in the form of a cloud, and electrical precipitating means for precipitating the cloud of condensed constituent from such gas, after each condensation of a constituent therefrom.

9i. An apparatus for recovering constitu- 105 ents of different condensability. from a gas, comprising a plurality of cooling devices, for successively cooling the gas to progressively lower temperatures.` corresponding to the temperatures of condensation of the respective constituent aforesaid, so as to form at each cooling action a' cloud of particles consisting of a constituent of the gas, and av precipitating means connected to receive the gas from each cooling means, to precipitate the cloud therein formed.

WALTER AUGUsT SCHMIDT. LINN BRADLEY.

fitnesses to signature of Valter August Schmidt:

TBL N. DREW, K. M. Mostri-3R. iVitnesses to signature of Linn Bradley:

ALFRED H. VHITE, J. VrBAT'rEN. 

